Answer: the dependent variable was the learning outcome.
Step-by-step explanation:
1) The dependent variable is the variable that is explained by the indepent variable.
The dependent variable is not changed or fixed by the experiment, but it is a response from the change in the independent variable.
2) The independent variable is the variable that can be changed arbitrarily (inside the physical restrictions).
In this case, the variable that is changed at will of a part (may be the own will of the students or an imposition of the teacher, or other reason, it does not matter), is the kind of activity to learn: either learning from a video game or from traditional classroom activities).
Therefore, the independent variable is the kind of learning mode.
On the other hand, the learning outcome is the variable studied. The experiment is meant to determine how the learning outcome is related or explained by the kind of learning activity.
Therefore, the learning outcome is the dependent variable.